ab slider is the best abs machine
I bought 1 a few yrs ago
and the tension in it was great
i got scared and said this machine works too fast and sold it to my co-worker
after i sold it , i could not find another 1 like it that works so fast
i could feel it in my hamstrings and my abs(belly) and hands all at the same time,
it is great
,that is the 1 with the string
because manufacturing seems to have been discontinued for it but this picture seems to be able to work, just get a shorter string